Method for melt loading explosives

ABSTRACT

A new method for melt loading explosives is provided by the use of a nozzle with a substantially cylindrical hollow body open at one end and having a restricted orifice at the other end which is provided with a plunger or poppet valve. The plunger has an actuating rod at one end and a plunger head at the other end. The plunger is slidably disposed in the nozzle with the actuating rod extending through the restricted orifice. The plunger head is of complementary shape to the restriction so that when the nozzle is in a normally upright position the plunger head due to hydraulic pressure of molten explosive normally seats against the nozzle restriction to prevent liquid flow therefrom. The actuating rod extending through the restricted orifice, when moved upward, causes the plunger head to move out of contact with the restriction to permit liquid explosive flow. This apparatus is used to facilitate the melt loading of explosives.

United @tates Patent [191 Fich'ter METHOD FOR MELT LOADKNG EXPLOSTVES mete? Primary Examiner-Leland A. Sebastian Att0rney-Harry M. Saragovitz et al.

[ 5 7 ABSTRACT A new method for melt loading explosives is provided by the use of a nozzle with a substantially cylindrical hollow body open at one end and having a restricted orifice at the other end which is provided with a plunger or poppet valve. The plunger has an actuating rod at one end and a plunger head at the other end. The plunger is slidably disposed in the nozzle with the actuating rod extending through the restricted orifice. The plunger head is of complementary shape to the restriction so that when the nozzle is in a normally upright position the plunger head due to hydraulic pressure of molten explosive normally seats against the nozzle restriction to prevent liquid flow therefrom. The actuating rod extending through the restricted orifice, when moved upward, causes the plunger head to move out of contact with the restriction to permit liquid explosive flow. This apparatus is used to facilitate the melt loading of explosives.

4 Claims, 3 Drawing Figures PATENTED APR 1 0 W5 4 2 6 2 2 4 a 2 J 2 0 M u h 5 2 AH I k I 0 m 3 2 METHOD FOR MELT LOADING EXPLOSKVES The invention described herein may be manufactured, used and licensed by or for The Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION Cast or melt-loaded explosives are generally defined as those having a melting point of approximately 100C or less and which are loaded in ammunition items by casting. Earlier melt loading systems of the art were operated on a batch basis with the explosive either being transferred from a kettle to a conductive rubber bucket and then from the bucket through a funnel into the item being loaded, or in the case of larger items such as bombs and large shells directly from the kettle through a funnel into the item being loaded.

The inherent slowness and the inconsistencies of this procedure led to the development and introduction of a continuous melt loading line. Generally, in this continuous process, the empty item is locked into place on a specially designed plate which is an integral part of a continuously moving conveyor. A combination funnelformer is placed on the item. The funnel-former on the bottom will, of course, be designed to have an outside diameter to provide a close fit with the specific item being loaded. The function of this funnel-former is generally to provide an excess space above the item which the explosive can fill to insure that the item will be completely full after cooling. Additionally, the funnel-former has a pan, with corresponding former holes, placed over the funnel-former so that any excess explosive will drip on the pan rather than on the outside of the former or the item itself. The funnel-former has an inner configuration and an inside diameter such that a void of a predetermined shape will be molded into the filled explosive item when cooled. In the past the explosive was fed continuously from a heated kettle through a manually actuated nozzle which was simply a large diameter flexible hose with a pinch clamp for a shut off. After loading, the items proceeded through a cooling box to solidify the molten explosive, then to an automatic device which separated the funnel-former from the item. The explosive material which had overflowed onto the pan and solidified was recovered for remelting and subsequent usage. The ammunition items were cast to their final configuration with only a small machining operation required to remove the break-off marks from the cast charge caused by the formers. The funnel-formers were removed manually from the item, the risers (excess explosives) removed and the former placed on a conveyor belt, which returned them to the beginning of the conveyor line. The loaded items were removed automatically from the conveyor plates and transported by separate conveyor belt to a packing area, for subsequent reuse. While the continuous process was more efficient than prior batch processes it was still not completely satisfactory. The pinch clamp nozzle used did not permit a rapid, positive closure of the loading operation. Because of the pinch clamp design a certain amount of explosive remained in the bottom of the hose after the clamp closed off the flow of molten explosive. This remainder usually overflowed from the funnel and was deposited on the pan, thus causing a relatively large quantity of explosive to be recovered after the final operation. This recovery step required a certain amount of effort on the part of four line operators, since it was necessary to remove the scrap explosive from the pan. This removal produced a fairly large amount of explosive dust in the area. Further, shut off of the pinch nozzle was not automatic and had to be gauged by the operator loading the item, so that uniformity of the quantity of explosive in each item varied widely.

It is, therefore, an object of this invention to provide a method for automatic shut off to the flow of molten explosive to the loaded items.

A further object is to provide a safe shut off valve having a minimum of moving parts and having any frictional contact of solid parts reduced to a minimum value.

Another object is to eliminate the necessity of excessive clean up operation and excessive recovery of scrap explosive due to overfilling of production items, thus increasing the efficiency of the continuous loading of munition items.

Other objects and many of the attendant advantages of my invention will be readily appreciated as the same become better understood by reference to the following description, wherein it is shown that the abovementioned objects are attained and the prior art deficiencies are overcome by the use of a conductor nozzle actuated by simple axial motion having essentially only one moving part by which extremely accurate control of molten explosive throughout is attained and very uniform filling of explosive items is accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the nozzle in closed position and a preferred workpiece.

FIG. 2 is a plan view of the nozzle or conduit along the line 22.

FIG. 3 is a cross-sectional view of the nozzle in open position.

DESCRIPTION OF A PREFERRED EMBODIMENT The method of my invention can best be shown through a description of the structure and function of the entire item together with the workpiece. As shown in FIG. 1 the nozzle 10 is composed of a substantially cylindrical hollow body or conduit 12 open at one end and having a restricted orifice 14 at the other end. The body 12 is provided with a slidably mounted poppet valve 16. The valve 16 is fabricated from an actuating rod 18 and a plunger head 20 fixed thereto. The actuating rod 18 has a cross-sectional diameter of such size, in relation to the restricted orifice 14, as to permit free flow of viscous fluid between the actuating rod 18 and the body 12 at such time as fluid has access to the restricted orifice 14. The plunger head 20 is fabricated of a complementary shape to the body 12 so'that when the nozzle 10 is in an upright position with the restricted orifice l4 downward the restricted orifice 14 will normally be cut off from fluid access from the body 12. The workpiece 22 to be filled with melted explosive is placed in a holder 24. An open mouthed drip pan 26 is permanently installed above the funnel-former 28. The funnel-former 28 having holes 30 therein is placed in abutting relationship to the workpiece 22, for the melt explosives to enter the workpiece 22. In FIG. 3v the nozzle or conduit 10 is shown in operation. A flexible hose 32 may be attached to the upper open end of the nozzle or conduit thus forming an extended conduit 10. An explosive melt 34 is introduced into the nozzle 10 through the body 12. As the actuating rod 18 is moved upward through the body 12 the plunger head 20 moves out of contact with the body 12 and clears the restrictive orifice 14 so that orifice 14 is now in fluid communication with the interior of the body 12, allowing molten explosive 34 to flow into the funnelformer 28 and through the holes 30 into the workpiece 22, thus filling the workpiece 22. After the proper amount of explosive 34 is introduced, the nozzle 10 is raised sufficiently to permit actuator rod 18 to descend thus reestablishing contact between the plunger head 20 and the body 12. This relative motion closes the popper valve 16 through hydraulic pressure of the explosive 34 and interrupts fluid communication of melted explosive 34 between the interior of the body 12 and the restrictive orifice 14. This method of closure with the poppet valve 16 at the terminating end of the conduit 12 prevents excess explosive remaining in the conduit after valve closure which in turn eliminates waste explosive building up in the former and dripping onto the splash pan. This step of waste elimination results in a number of advantages, notably increased production of the order of 100 percent due to increased speed of the conveyor belt, and elimination of excess personnel, cleaning steps and redissolution steps.

The nozzle is preferably made of heat resistant, nonsparking, conductive materials to prevent build up of static electricity and to prevent material breakdown or reaction through contact with the hot explosive compositions. A preferable material is stainless steel .but other types of materials meeting the above-listed criteria may be used. The poppet valve is preferably made of a material which is conductive, heat resistant, non-sparking and will not react with the molten explosive. Additionally, the plunger head must minimize friction. Preferred materials for the poppet valve are teflon for the plunger head and aluminum for the actuating rod. However, any materials meeting the specified criteria may be used.

The explosives which may be loaded by using the method of my invention preferably have a melting point below about 100C.

In addition to having the capability of melt loading these explosives with a melting point of 100C or less, other explosive mixtures containing at least one of the low melting components in a fairly high proportion can be loaded in this facility. For example, Amatol, Baratol, Baronal, Composition B, Cyclotol, DBX, Ednatol, HTA-3, Octol, Pentolite, Picratol, Plumbatol, PTX-l, PTX-2, Tetrytol, TNT, Torpex, Tritonal. The compositions of these explosives are listed in an Engineering Design Handbook entitled Explosives Series, Properties of Explosives of Military Interest," AMC Pamphlet AMCP 706-177, Jan. I971, distributed from Headquarters U.S. Army Materiel Command.

Summarizing, the method of this invention employs a conduit having a restricted opening in one end and terminating in a poppet valve to continuously load molten explosives contained in the conduit into a munition. The poppet valve is mounted in the restricted end of the conduit and opens inside of the conduit in response to axial pressure thus allowmg the explosive to pass through the conduit into the item to be loaded. The hydraulic pressure of the contained explosive will cause the poppet valve to close as soon as the axial pressure is removed, thereby substantially instantaneously interrupting the explosive flow and preventing excess explosive to flow into and around the item. Additionally this type of rapid closure promotes more uniform loading in each of the items.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as shown and described.

I claim:

l. A method of filling munitions with molten explosive, comprising:

introducing a continuous stream of said molten explosive into a conduit, terminating with an externally actuated poppet valve opening into said conduit; positioning said poppet valve over said munition; applying axial force to unseat said poppet valve to permit flow of said explosive into said munition to a predetermined level and removing said axial force to allow the hydraulic force of said explosive to reseat said poppet valve thereby interrupting the flow of said explosive and providing a substantially instantaneous shutoff of said explosive.

2. A method as defined'in claim 1 wherein said munition has an opening therein and said positioning step is accomplishedby placing said poppet valve over the opening in said munition so that the longitudinal axis of said poppet valve is normal to the transverse axis of said opening.

3. A method as defined in claim 1 wherein the application of said axial force is accomplished by contacting said poppet valve with said munition to unseat said poppet valve and the removal of said axial force is accomplished by removing said poppet valve from contact with said munition.

4. A method as defined in claim 1 wherein said molten explosive has a melting point below about C. 

1. A method of filling munitions with molten explosive, comprising: introducing a continuous stream of said molten explosive into a conduit, terminating with an externally actuated poppet valve opening into said conduit; positioning said poppet valve over said munition; applying axial force to unseat said poppet valve to permit flow of said explosive into said munition to a predetermined level and removing said axial force to allow the hydraulic force of said explosive to reseat said poppet valve thereby interrupting the flow of said explosive and providing a substantially instantaneous shutoff of said explosive.
 2. A method as defined in claim 1 wherein said munition has an opening therein and said positioning step is accomplished by placing said poppet valve over the opening in said munition so that the longitudinal axis of said poppet valve is normal to the transverse axis of said opening.
 3. A method as defined in claim 1 wherein the application of said axial force is accomplished by contacting said poppet valve with said munition to unseat said poppet valve and the removal of said axial force is accomplished by removing said poppet valve from contact with said munition.
 4. A method as defined in claim 1 wherein said molten explosive has a melting point below about 100*C. 